Coupling devices of the kind outlined above are well known. Other examples are coupling devices of hose-coupling type, i.e. in the form of a strap that is tightened by means of a screw. One problem found in coupling devices available on the market today is, however, that they are comparatively inconvenient to put in place, particularly in narrow spaces. Another problem is the difficulty to establish whether the coupling is correctly mounted, i.e. whether the coupling device grasps the coupling joint sufficiently.